In addition to electronically controlled brake systems which make available functions such as a brake slip control system (ABS) which prevents the wheels locking during full braking, and a vehicle movement dynamics control system (ESC) which acts in a stabilizing fashion on the motor vehicle during dynamic driving maneuvers by means of selective braking interventions, motor vehicles increasingly have an environment sensor system with which other road users and nonmovable obstacles are detected and the positions and speeds thereof with respect to the driver's own vehicle can be determined.
The networking of the environment sensor system with an electronically controlled brake system permits the distance from the motor vehicle traveling ahead to be controlled (ACC), a warning to be issued to the driver when particularly critical situations occur and automatic initiation of an emergency braking operation when there is a risk of a collision. In order to avoid incorrect interventions, such an emergency braking assistant (EBA) is only allowed to engage late, i.e. at the smallest possible distance from the obstacle, as a result of which in many situations a collision with the obstacle or the other road user by simply braking can only be attenuated and not avoided despite this driver assistance.
There are various reasons for this:                Maintaining an ideal distance from the vehicle traveling ahead is not practical in dense traffic.        An oncoming vehicle is overlooked at the start of an overtaking maneuver.        The distance calculation of the driver assistance system assumes that the coefficient of friction is that of a planar and dry roadway, with the braking distance being longer on a slippery roadway than the distance from the engagement point.        
In order to prevent a collision an avoidance maneuver is therefore frequently necessary in addition to the braking operation. Furthermore, in many situations a collision can be prevented by means of an avoidance maneuver, even without braking. Many drivers experience such an emergency avoidance situation very rarely and when they suddenly come across an obstacle they react intuitively with an excessively dynamic steering input.
At high speeds this can lead to violent vehicle reactions, in particular during the subsequent steering back.
For this reason, systems have already been developed which assist the driver during an avoidance maneuver even without an environment sensor system. DE 101 19 907 B4, which is incorporated by reference, therefore discloses a method for controlling the driving stability in which during stable cornering it is determined whether there is a tendency towards subsequent unstable driving behavior on the basis of a steering angle speed and a measured lateral acceleration. In this case, a braking pre-engagement already takes place during stable driving behavior, wherein the braking pre-engagement is ended if at least one change of direction of a yaw rate is detected after a yaw rate maximum and a model-based lateral acceleration is equal to or lower than a limiting value.
A further development of the method is disclosed in WO 2004/074059, which is incorporated by reference. In this context, a driving situation senses characteristic variables and determines a driver reaction therefrom. If a critical driving situation is to be expected on the basis of the expected driving behavior, braking interventions and/or engine interventions are already performed during stable driving behavior. The interventions are performed as a function of an expected lateral acceleration which contains the theoretical lateral acceleration which the vehicle will have in the future if the driver continues to turn in or turn out with a uniform steering angle speed. The described methods can damp excessively violent steering maneuvers of the driver and therefore avoid skidding or tipping over of the vehicle, but the avoidance of incorrect interventions presents a problem. If the driver steers too hesitantly this can lead to a partial coverage collision.
DE 10 2010 028 384 A1, which is incorporated by reference, discloses a method for closed-loop and/or open-loop control of the driving stability of a vehicle and avoiding collisions with an object located in the lane. On the basis of environment signals it is determined whether a situation critical in terms of vehicle movement dynamics, in particular an imminent collision, is present, and when a critical situation is present an avoidance path is determined. Furthermore, pressures for individual brakes of the vehicle are determined on the basis of a plurality of input variables, and preparatory measures of the vehicle movement dynamics controller such as dynamic switching over of control parameters are activated if the situation which is critical in terms of vehicle movement dynamics is present. In one preferred embodiment of the invention, a setpoint steering angle, which is set by means of an active steering system, is determined on the basis of the determined avoidance path. An autonomous steering intervention is critical in terms of product liability and acceptance by the driver.